UPDATE 10:03 AM PT: Sly did not make it to court this morning -- but his attorney did ... and told the judge Sly is currently being hospitalized for heart issues. The judge ordered Sly to appear on Wednesday instead.

Sly Stone -- leader of the group Sly and the Family Stone -- is slated to appear in an L.A. courtroom today after the singer was arrested for cocaine possession back in April ... TMZ has learned.

Stone -- real name Sylvester Stewart -- was arrested on April 1 ... after LAPD officers say they found freebase cocaine on the 68-year-old during a vehicle search.

TMZ spoke with Sly's attorney, James Silverstein, who tells us Stone was riding in a buddy's camper vehicle with some friends ... when it was pulled over for a routine traffic violation.